1. Field of the Invention
The present invention relates to flash beacons used primarily for tall structure warning and for navigational purposes. It relates particularly to such beacons having different modes of operation for different visibility conditions.
2. Relation to the Prior Art
With the speed of modern aircraft, beacons are needed even in the best of daylight visibility and the red lights used for illuminationg tall structures are no longer adequate. For the most attention-getting efficiency, flash lamps are used with high energy in very short flashes. At night, single short flashes attract attention, but produce their own problems. Bright short flashes at night have a saturating effect on vision that makes them difficult to locate spatially. U.S. Pat. No. 3,846,750 of the present inventor describes a beacon using bursts of flashes at night and single flashes of much higher intensity in daylight. The nightime burst of low level flashes is spread over a sufficient time interval to allow precise visual spatial location. The low intensity level in the burst flashes is not highly efficient for initial attention attraction.